Microsoft announced that OneDrive is doubling its storage space again. You get 15 GB for free accounts, plus an additional 15 GB for the Camera Roll bonus. The company recently upgraded free storage space to 15 GB, and is now offering an additional 15 GB of space if you set your camera roll to backup to OneDrive automatically.

The promotion is for a limited time, and mainly aimed at iPhone users. However, it also covers Android and Windows Phone users. If you already use OneDrive for your camera roll on Windows Phone or Android, you will see your storage go up to 30 GB.

OneDrive is available for every mobile platform: Android, iOS, Windows Phone, Blackberry, and even Amazon’s Fire Phone and tablets.

As previously mentioned, this offer is mainly for new iPhone users, according to the announcement on the Microsoft OneDrive Blog:

All you have to do is sign up for OneDrive and activate the auto upload feature for your camera roll sometime between now and the end of September, and you will get 30 GB of free OneDrive storage moving forward (15 GB base and 15 GB camera roll bonus). For those getting ready to install iOS8, this means you won’t have to delete a bunch of photos or apps to make room for the upgrade.

The cool thing, also in the same blog post, is those of us who already use OneDrive will get the additional storage space. Also, if you set up your phone to auto backup your photos and videos to OneDrive, you too get the additional space:

Not an iPhone user? Don’t worry, we’ve got you covered. This also applies to anyone who already uses the OneDrive camera roll on Windows Phone (Windows Phone Store), Android (Google Play Store) and Windows (Download) – you’ll see your storage go up as well. Same for any existing iPhone users who backup their photos to OneDrive.

The reason we recommend uploading your photos and videos to OneDrive from whatever mobile device you use, is that OneDrive is available on all platforms. It gives you one central location for storing them, and it’s very easy to share the photos with anyone.

This is a limited time offer, and Microsoft isn’t being clear on how long the deal will last so you’ll want to hop on it as soon as you can. Again, if you aren’t’ sure how to set up your iPhone or other mobile platform, make sure to read our walkthrough:

So I went ahead and tried to add photos to sync to my OneDrive from my iPhone, and while it’s just super slow. Other than the free space I can’t see any reason to do this first what I’m currently doing with Dropbox.